U.S. Pat. No. 5,888,424 discloses a fluorescent object (i.e., an object that generates fluorescence and reflects incident light when illuminated) formed of a matrix material such as plastic that contains, for example, a dispersed material such as a fluorescent powder. For example, a fluorescent object is disclosed that is formed of a fluororesin composition containing an inorganic phosphorus substance that produces fluorescent light when excited by incident light. Also, U.S. Pat. No. 5,462,705 discloses another fluorescent object wherein, to produce the fluorescent object, blended powder is placed within a mold and compressed so that the density of the molded object is adjusted so that the porosity of the fluorescent object is in the range of 30% to 50%. Then, the compressed powder is extracted from the mold and sintered on a ceramic plate in the atmosphere so as to produce the fluorescent object.
Furthermore, U.S. Patent Publication 2005/0117028 discloses a fluorescent object that may be used for color balance adjustment of a fluorescent endoscope system.
The inventions described in U.S. Pat. Nos. 5,888,424 and 5,462,705 each require a heat-treatment process (i.e., a molding process), such as fusion by heating or hardening by heating, making it necessary to select an inorganic fluorescent powder that will not become denatured during the heat-treatment process. Further, in the invention described in U.S. Pat. No. 5,462,705, a dispersant is added so as not to separate or agglutinate the inorganic fluorescent powder. Adding such a dispersant may induce the generation of fluorescent noise or cause the plastic to deteriorate. Further, since a heat treatment process is required, there is a cost increase. In U.S. Patent Publication 2005/0117028, there is no description regarding the material of the fluorescent object. However, in general, fluorescent materials have a problem in that, when excitation light is irradiated onto the fluorescent object, the intensity of fluorescence deteriorates over time due to photo bleaching.